In packing semiconductor elements into an electronic circuit, a TAB (Tape Automated Bonding) technique has been known, by which a tape carrier semiconductor device is obtained by bonding and mounting a semiconductor element on a flexible printed board (so called tape carrier)
Tape carrier semiconductor devices obtained by the TAB technique include a COF (Chip On FPC (Flexible Printed Circuit)), a TCP (Tape Carrier Package), etc. In the COF, the tape carrier is bonded to the semiconductor element electrode and a wiring pattern on the bonded portion is backed with a tape carrier material. On the other hand, in the TCP the tape carrier material is bonded to the semiconductor element electrode and a through-hole is provided in the bonded portion where the semiconductor element is mounted. Further, a top end of a wiring pattern called an inner lead which protrudes to form a cantilever is bonded to the semiconductor element electrode.
The tape carrier semiconductor devices are mainly used as a liquid crystal driver, a thermal head printer, etc.
The tape carrier semiconductor device is completed in the following manner. That is, identical wiring patterns are formed successively on a lengthy tape (tape carrier material) at regular intervals in a single direction with respect to a direction in which the tape is fed, and semiconductor elements are mounted at specific positions of the wiring patterns. Then, the tape carrier semiconductor device is completed when punched out individually from the lengthy tape. Thus, the tape carrier semiconductor devices formed on the tape carrier are designed along a single direction with respect to a direction in which the tape is fed. In case that the tape carrier semiconductor device thus completed is used for a liquid crystal panel, for example, it is connected to the liquid crystal panel at one side end, and to the printed board or the like at the other side end.
Because the tape carrier semiconductor device is flexible, it is designed on the provision that it will be bent when mounted, and therefore, given with high design flexibility. Thus, in the case where a layout of the tape carrier semiconductor devices are designed on a lengthy tape carrier and each tape carrier semiconductor device is not necessarily a rectangle, which is the area shape in which the tape carrier is utilized efficiently, but can be of an L-shape, a T-shape, a triangular shape, etc.
However, when the tape carrier semiconductor devices of arbitrary shapes are aligned in a single direction, as has been discussed, a useless area which is not used in manufacturing the tape carrier semiconductor devices is formed on the tape carrier. For example, in the case where COFs 51 of a shape shown in FIG. 11(a) are aligned on the tape carrier, then a conventional layout is as the one shown in FIG. 11(b). That is, in this case, a useless area (indicated by diagonal lines) 52 is formed on the tape carrier.
When the manufacturing procedure and used materials of the tape carrier are concerned, the tape carrier is manufactured in the form of a lengthy tape from reel to reel, and therefore, the cost thereof increases in proportion to the tape area. Thus, even if some areas of the tape carrier are not used in manufacturing the tape carrier semiconductor devices, the cost wasted on such areas is included in the manufacturing cost. Therefore, the manufacturing cost of the tape carrier semiconductor devices increases as the areas which are not used in manufacturing increases. The useless areas may be reduced by designing the tape carrier semiconductor devices in a shape with which the tape carrier is utilized efficiently (for example, rectangles). However, this is not preferable, because the design flexibility given to the tape carrier semiconductor devices as benefits will be lost.
Japanese Laid-open Utility Model No. 82852/1994 (Japanese Official Gazette Jitsukaihei No. 6-82852, publishing date: Nov. 25, 1994) discloses a technique for aligning the semiconductor device TABs in more than one row in the width direction of the tape carrier as a method of minimizing unused areas on the tape carrier and conducting an electrical test on more than one TAB simultaneously. However, the above publication does not solve the problem that useless areas are readily formed on the tape area if the tape carrier semiconductor devices are of arbitrary shapes, because each TAB is aligned in one specific direction with respect to a direction in which the tape is fed, and each TAB is of a rectangular shape with which the tape area can be utilized efficiently.